The more abstract concept of complementarity does appear to be woven in the fabric of the universe. At least if it's not, then math working so well is really surprising.
Sex is a case of biotic complementarity. I don't know much about slime molds, but I'm willing to bet there is all kind of complementarity in their organization.
But complementarity doesn't have to be binary, which is the point under contention here. It is a scientific fact that gender and even sex in human populations, while having a strong binary tendency, is not in any way an absolute binary.
Binary complementarity is no more woven into the fabric of the universe than any other symmetry that you see in nature. Gravity is unipolar, electromagnetism is dipolar and the strong force is multipolar. In fact, if you look at electroweak theory (which breaks into E&M and the Weak Force) the bipolar character of the E&M field is less fundamental that it might appear.
Sex is a case of biotic complementarity. I don't know much about slime molds, but I'm willing to bet there is all kind of complementarity in their organization.